As mobile phones are becoming more popular, the requirements to acoustic quality of the mobile phones are gradually increased. Besides, the hearing aid technology is gradually becoming mature. Therefore, demands for high quality mini-sized microphones are sharply increased. Capacitive microphones manufactured by MEMS technologies have advantages including light weight, small volume, and better signal quality, which all make the MEMS microphone become the mainstream of the market of mini-sized microphone.
FIG. 5 is a schematic view of a conventional MEMS microphone packaging structure. The MEMS microphone packaging structure includes a base 90, a MEMS microphone chip 91, a controlling chip 92 and a packaging cover 93. The MEMS microphone chip 91 is sealed in a package formed by the base 90 and the packaging cover 93. The MEMS microphone chip 91 is controlled by the controlling chip 92. In this conventional structure, the MEMS microphone chip 91 and the controlling chip 92 are separately disposed on the base 90 and covered by the packaging cover 93 for protection.
However, the packaging structure has three disadvantages as follows: 1. The MEMS microphone chip 91 is typically disposed adjacent to the controlling chip 92, therefore a sufficiently large base 90 is needed for them to dispose on, thus the dimensions of the MEMS microphone packaging structure is not easy to reduce. 2. Wires 96 and pads 97 for connecting the MEMS microphone chip 91 and the controlling chip 92 to the base 90 are exposed in a containing space 94 of the MEMS microphone packaging structure. Moisture and dusts from the outside may enter the containing space 94 through a sound penetrating hole 95 formed on the base 90, and oxidize or damage the wires 96 and pads 97, and thus reduce the reliability. Accordingly, gold or other precious metal is used for making the pads 97 to prevent corrosion, however, the cost is high and the bonded wires may not be guaranteed not to detach. 3. The mechanical properties of the base 90 and the packaging cover 93 are not the same. In order to prevent thermal deformation of the base 90, the thickness of the base 90 is made thicker, and that consequently causes the thicker thickness of the entire packaging structure. There is room for improving the cost effectiveness and the reliability.
Therefore, it is needed to provide a novel MEMS microphone packaging structure to solve the above mentioned problem.